doc: broken link on troubleshooting-mon page

doc: broken link on troubleshooting-mon page
Fixes: https://tracker.ceph.com/issues/37451
This fix involves adding :ref: labels to the add-or-rm-mons.rst
page. I also added :ref: labels for other headings within
add-or-rm-mons.rst (for future reference).

Signed-off-by: James McClune <jmcclune@mcclunetechnologies.net>
(cherry picked from commit ca05e456969a721631f5e9882c896cab76a4a3dc)

Conflicts:
	doc/rados/troubleshooting/troubleshooting-mon.rst
		Fixed the :ref: sentence and removed the _replace line.